Apparatus and method for generating a stabilized sanitizing solution

Abstract

The present invention provides a method utilizing Cylindrical Electrolysis cells for the generation of Hypochlorous Acid (HOCL) solutions having excellent sanitizing properties and a shelf life of 24 months when bottled. The electrolysis cells consist of at least two cylindrical electrodes with at least one cylindrical ion-selective membrane arranged co-axially between them. A cation-selective or anion-selective membrane separates the cathode chamber from the anode chamber allowing only selective ions to move from one chamber to another. A three section end piece facilitate the assembly of the cylindrical electrolysis cell and enables easy inspection and replacement of the ion-selective membranes. The method allows production of different concentrations of Hypochlorous Acid solutions with a pH value ranging from 3.5 to 7.5 and an Redox Oxidation Potential between +700 and +1200 mV when an aqueous sodium chloride or potassium chloride solution is treated.

We claim: 
     
         1 . An apparatus for generating a stabilized sanitizing solution comprising: two cylindrical electrolysis cells having an outer cylindrical electrode separated from an inner cylindrical electrode by a cylindrical ion-selective membrane arranged coaxially one within the other to create a cathode chamber and an anode chamber; a pair of end pieces to each of said cells where a space between said inner cylindrical electrode and said cylindrical ion-selective membrane and a space between the ion-selective membrane and the outer cylindrical electrode defines anode and cathode chambers; wherein one of said electrodes functions as an anode and the other electrode functions as a cathode to form a stabilized sanitizing solution having an extended shelf life from a diluted brine drawn through said electrolysis cells. 
     
     
         2 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said anode and cathode are constructed from a titanium base activated with a mixed metal oxide coating structure including a mixture of ruthenium, iridium, titanium, tantalum, and rhodium. 
     
     
         3 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said ion-selective membrane in said electrolysis cells consists of a cylindrical cation-selective membrane made of polymer or perfluorinated membrane sheet reinforced with or without polytetrafluoroethylene. 
     
     
         4 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said ion-selective membrane in said electrolysis cells consists of a cylindrical anion-selective membrane made of polymer or perfluorinated membrane sheet reinforced with or without polytetrafluoroethylene. 
     
     
         5 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said cylindrical ion-selective membranes are mounted on a bushing that thread into said cylindrical ion-selective membrane to form a non leaking seal. 
     
     
         6 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said cylindrical ion-selective membrane is construed from ion-selective membrane sheet that is stretched and sealed to form a cylinder that is capable of sustaining up to 50 psi pressure. 
     
     
         7 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said the ion-selective membrane sheet is sealed around the outside or inside of a perforated porous tube to form a leak free seal with the tube, said tube fits into an O-ring or gasket to form a non leaking seal with the end piece of said electrolysis cell. 
     
     
         8 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said end piece comprises three stackable sections of complimentary topography with at least one seal forming feature at every interface between adjacent sections wherein said seal is selected from the group of a compressible ridge, a gasket, or an O-ring. 
     
     
         9 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein said tubes and end pieces are selected from the group of Polyvinyl Chloride (PVC), Acetal, Nylon or Poly Carbonate. 
     
     
         10 . The apparatus for generating a stabilized sanitizing solution according to  claim 7  wherein said gaskets and O-rings are selected from the group of Ethylene Propylene (EPDM), Nitrile (BUNA-N), Fluorocarbon (FKM) or combination of a plastic and a rubber. 
     
     
         11 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein changing the sequence of the electrolyses stages generates a solution with different pH, free available chlorine content, redox-potential, conductivity, osmolality and shelf life. 
     
     
         12 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein aqueous sodium chloride or potassium chloride solution is supplied to the cathode chambers and anode chambers at a lower end piece of the electrolysis cells and cleaning solutions (NAOH) and sanitizing solutions (HOCL) are obtained from an upper end piece of the electrolysis cells. 
     
     
         13 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein a spiral feed of the aqueous brine is fed to the anode and cathode chambers using tangential inlet and outlet ports. 
     
     
         14 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein the current is a direct current applied across the electrodes. 
     
     
         15 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein free available chlorine content is regulated by altering voltage, volume and electrical conductivity of aqueous sodium chloride or potassium chloride solution by controlled injection of a saturated brine solution into softened water prior to passing a dilute brine solution through the anode chambers and cathode chambers and whereas the current across the electrodes is at least 20 amps. 
     
     
         16 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein the cathode chamber comprises an inlet fitting connected to a tube that passes tangentially through a specific section of the lower end piece to communicate with the cathode chamber through an aperture and wherein the anode chamber comprises an inlet fitting connected to a tube that passes tangentially through a specific section of the lower end piece to communicate with the anode chamber through an aperture 
     
     
         17 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein the cathode chamber comprises an outlet fitting connected to an tube that passes tangentially through a specific section of the upper end piece to communicate with the cathode chamber through an aperture and wherein the anode chamber comprises an outlet fitting connected to a tube that passes tangentially through a specific section of the upper end piece to communicate with the anode chamber through an aperture. 
     
     
         18 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein ports address spaces through said end pieces or through said electrode tubes adjacent to the site of insertion of said electrode tubes into said end pieces. 
     
     
         19 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein entrance ports direct the flow of said fluid at an angle of 0 to 15 degrees relative to the plane of seats of said end pieces. 
     
     
         20 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein solution is a diluted hypochlorous acid. 
     
     
         21 . The apparatus for generating a stabilized sanitizing solution according to  claim 1  wherein solution is sodium hydroxide. 
     
     
         22 . A method for generating a stabilized sanitizing solution having an extended shelf life, said method comprising the steps of:
 arranging two cylindrical electrolysis cells having an outer cylindrical electrode separated from an inner cylindrical electrode by a cylindrical ion-selective membrane arranged coaxially one within the other to create a cathode chamber and an anode chamber;   providing a pair of end pieces to each of said cells where a space between said inner cylindrical electrode and said cylindrical ion-selective membrane and a space between the ion-selective membrane and the outer cylindrical electrode defines anode and cathode chambers;   introducing a diluted brine solution into one said end piece wherein one of said electrodes functions as an anode and the other electrode functions as a cathode to form a stabilized solution having a prolonged shelf life.   
     
     
         23 . The method for generating a stabilized sanitizing solution according to  claim 22  wherein said diluted brine solution is a saturated chloride solution injected into softened water to make a aqueous chloride solution and wherein the concentration of the chloride solution passing through cathode and anode chambers is maximal 15 g/L. 
     
     
         24 . The method for generating a stabilized sanitizing solution according to  claim 23  wherein said saturated chloride solution is sodium chloride. 
     
     
         25 . The method for generating a stabilized sanitizing solution according to  claim 23  wherein said saturated chloride solution is potassium chloride. 
     
     
         26 . The method for generating a stabilized sanitizing solution according to  claim 23  wherein the concentration of the chloride solution is controlled by measurement of the electrical conductivity of the diluted brine solution or the current measured across the electrodes in the electrolysis cells using a variable speed peristaltic pump. 
     
     
         27 . The method for generating a stabilized sanitizing solution according to  claim 22  wherein 5 to 15% of the liquid is an alkaline cleaning solution consisting of Sodium Hydroxide and having a negative redox potential ranging from −700 to −900 mV. 
     
     
         28 . The method for generating a stabilized sanitizing solution according to  claim 22  wherein 85% to 95% of the liquid is an neutral sanitizing solution consisting of Hypochlorous Acid having a free-active-chlorine content of 90 to 900 ppm and a positive redox potential ranging from +700 to +1200 mV. 
     
     
         29 . The method for generating a stabilized sanitizing solution according to  claim 22  wherein free available chlorine content is regulated by altering voltage, volume and electrical conductivity of the solution by controlled injection of a saturated brine solution into softened water prior to passing a dilute brine solution through the anode chambers and cathode chambers and whereas the current across the electrodes is at least 20 amps. 
     
     
         30 . A method for generating a stabilized sanitizing solution comprising the steps of: constructing several electrolysis stages for converting a diluted brine solution into a stabilized Hypochlorous Acid solution by passing and electrolyzing a diluted brine solution through one cathode chamber and two anode chambers of two cylindrical electrolyses cells; applying a current across the electrodes of said electrolysis cells; forming a sealing engagement between an end piece to said chamber, a cylindrical electrodes and an ion-selective membrane wherein said end piece has a lateral inlet through an outer wall thereof, said inlet being provided with a fitting for tangential feeding of the brine solution to the inside of the end piece, and wherein two pairs of ports for entrance or exit of fluid are situated in an upper and lower end piece comprising an external fitting for attachment of a hose or pipe, wherein said first pair of ports at opposite ends of said assembly internally addresses a space between said outer electrode tube and the ion-selective membrane and said second pair of ports at opposite ends of said assembly internally addresses a space between said ion-selective membrane and said inner electrode tube. 
     
     
         31 . The method of  claim 30 , wherein diluted Hypochlorous Acid solutions are generated with different pH, free available chlorine content, redox-potential, conductivity, osmolality and shelf life by changing the flow patterns through the electrolyses cells and thus changing the sequence of the electrolyses stages that the diluted brine solution undergoes. 
     
     
         32 . The method of  claim 31 , wherein a saturated sodium chloride or potassium chloride solution is injected into softened water to make a aqueous sodium chloride or potassium chloride solution and wherein the concentration of the sodium chloride or potassium chloride solution passing through cathode and anode chambers is maximal 15 g/L. 
     
     
         33 . The method of  claim 32 , whereas the concentration of the sodium chloride or potassium chloride solution is controlled by measurement of the electrical conductivity of the diluted brine solution or the current measured across the electrodes in the electrolysis cells using a variable speed peristaltic pump. 
     
     
         34 . The method of  claim 30 , wherein 5 to 15% of the liquid is an alkaline cleaning solution consisting of Sodium Hydroxide and having a negative redox potential ranging from −700 to −900 mV. 
     
     
         35 . The method of  claim 30 , wherein 85% to 95% of the liquid is an neutral sanitizing solution consisting of Hypochlorous Acid having a free-active-chlorine content of 90 to 900 ppm and a positive redox potential ranging from +700 to +1200 mV. 
     
     
         36 . The method of  claim 30 , wherein aqueous sodium chloride or potassium chloride solution is supplied to the cathode chambers and anode chambers at a lower end piece of the electrolysis cells and cleaning solutions (NAOH) and sanitizing solutions (HOCL) are obtained from the upper end piece of the electrolysis cells. 
     
     
         37 . The method of  claim 30 , wherein a spiral feed of the aqueous sodium chloride or potassium chloride solution is fed to the anode and cathode chambers using tangential inlet and outlet ports 
     
     
         38 . The method of  claim 30 , wherein the current is a direct current is applied across the electrodes. 
     
     
         39 . The method of  claim 30 , wherein the free available chlorine content is regulated by altering the voltage, volume and electrical conductivity of aqueous sodium chloride or potassium chloride solution by controlled injection of a saturated brine solution into softened water prior to passing a dilute brine solution through the anode chambers and cathode chambers and whereas the current across the electrodes is at least 20 amps.